There is an episode of Rork that you cannot find in the albums, Les oubliés...

Andreas: Yes, that was for a Super Tintin/Kuifje. I made it at the time
I was working on Cromwell Stone. That's why the drawings are somewhat
different. They are less detailed, made somewhat faster.
That was a first attempt to bring Rork back to life, a sort of first episode.
I wanted to make more of them for those Super Tintin/Kuifjes, a different
story every time. But that was cancelled. That's why it is an
episode somewhat unconnected from the rest.
It doesn't fit anywhere in the series as a whole.